1. Field of the Invention
The present invention relates generally to processing sheet material and, more particularly, to a sheet folding apparatus using pivot arm fold rollers.
2. Background Information
A system for finishing printed sheets into booklets is described in PCT Document No. WO 00/18583 (Trovinger et al.). The Trovinger PCT includes an operation where individual booklet sheets are folded using two drive motor assemblies. A first vertical drive motor assembly operates to immobilize a sheet by pressing it against a fold blade with a folder assembly. This first vertical drive motor assembly moves a set of fold rollers into contact with both the sheet and a longitudinal fold blade. The axes of rotation for the fold rollers are perpendicular to the fold blade used to fold each sheet. A second horizontal drive motor then operates to deform the sheet against the fold blade by reciprocating the set of fold rollers, which have been placed into contact with the sheet, back and forth along the fold blade to in effect crease the sheet. The number and spacing of these rollers are such that during horizontal movement of the fold rollers, at least one fold roller passes over every point along the portion of a sheet where a fold is to be formed.
The system described in the Trovinger PCT uses two separate motors to establish linear motion of fold rollers in two axes to create a fold. The time required to create a fold is the cumulative time of moving a folder assembly vertically and moving the fold rollers horizontally to crease the sheet.
It would be desirable to reduce the apparatus cost and the time required to form a fold in a sheet.
Accordingly, the present invention is directed to an apparatus that folds sheet material by displacing fold rollers along a fold blade using pivot arms. In this way, only one motor is required to establish linear motion of fold rollers in two axes to create a fold.
According to one embodiment of the present invention, a system for folding sheet material is provided, comprising a fold blade, a fold roller, and drive means for moving at least one of the fold blade and the fold roller along a first path into operative communication with one another, wherein the operative communication causes displacement of the fold roller along a longitudinal axis of the fold blade.
According to another embodiment of the present invention, a method for folding a sheet of material, comprising the steps of feeding a sheet material into an area between a fold roller and a fold blade, and moving the fold roller and the fold blade relative to one another to form a fold in the sheet using the fold blade, wherein an operative communication between the fold roller and the fold blade causes displacement of the fold roller along a longitudinal axis of the fold blade.